How To Let GSM Serve The People That Other Networks Can’t Reach

Mobile telephony has transformed access to communication in emerging markets.  In 1994, there were more telephone lines in New York City than in the whole of Africa.  These days, about two thirds of the population in sub-Saharan Africa is covered by a mobile phone signal.  That’s an amazing and profound change yet there are still millions of people who don’t have access to mobile networks.  Why is that?  Typically, the reason boils down to the fact that a business case doesn’t exist for mobile network operators to extend coverage to that area.  That might be because it is sparsely populated,  or in a hilly region that is expensive to cover, or because ability to pay is very low or some combination of the above.  Here are some low-risk things that regulators can do to help GSM services reach the unserved.

Social-Purpose Licenses For Rural Access

Low-cost alternative GSM technologies have existed for some time and there are a variety of startups in this space including Range Networks, Vanu, Endaga, Fairwaves, and others.   Some are based on popular Open Source software projects like OpenBTS and OpenBSC.  Manufacturers like NuRan Wireless are producing low-cost radio platforms that can serve as robust platforms for these Open Source initiatives.  The result is that it is possible to put up a DIY GSM base station for a few thousand dollars.  What holds these startups back though is the fact that the popular GSM spectrum bands have largely been assigned to existing Mobile Network Operators (MNOs).   Low-cost GSM startups like those mentioned above are left with the option of trying to sell their technology to incumbents, whose supply chains are pretty closely tied to big equipment suppliers like Huawei et al.  Or they can try to go it alone and find a sympathetic regulator but, to date, sympathetic regulators have been a bit thin on the ground.

That all changed last week, when the Mexican communications regulator, IFETEL, published their frequency plan for 2015.  IFETEL have set aside 2 x 5MHz of spectrum in the 800MHz band, specifically (824-849 and 869-894 MHz) for “social” use.  The criteria are that the communities being served must be less than 2500 people or be designated as an indigenous region or designated as a priority zone.  Small cell GSM to rural areas has already been going on for some time.  Rhizomatica, a non-profit organisation that has been providing GSM services to indigenous communities around Oaxaca since 2012.  Until last week they were doing it under a special dispensation from IFETEL but now the allocation of spectrum to this purpose is official and any organisation may apply for access to this spectrum under the conditions specified.  2 x 5MHz spectrum is not a huge amount of spectrum compared to the big operators where 2 x 10MHz or more is common but it is plenty for smaller communities.

Rhizomatica have played a critical role both in engaging with the regulatory change process and in providing the regulator with a successful model to base their regulatory reform on.  What IFETEL have done is groundbreaking in terms of regulation. This opens the doors to community entrepreneurial efforts to solve their own connectivity problems.

Rhizomatica are spreading rapidly in the Oaxaca region serving over 15 communities now. Peter Bloom, the founder of Rhizomatica, had this to say about IFETEL’s announcement:

 Rural areas have traditionally been no-go areas for incumbent telcos, and this forward-looking approach by the IFETEL allows other actors, including the communities themselves, to provide affordable access to communication services by having direct access to spectrum. This will lead to more people being connected which will bring both social and economic benefits to underserved areas.  If the role of regulators is to maximize the benefit that society obtains from the use of radio spectrum, then this is a step in the right direction.

When I look at the spectrum allocations for countries in sub-Saharan Africa, most of them have sufficient wiggle room in their GSM allocations that they could do this.   The allocations of spectrum are small enough that this is unlikely to infringe on the requirements of any existing operators.  What if remote communities all over Africa began to manage their own communication infrastructure?

Unlicensed GSM

Licensed spectrum is not the only way to take better advantage of GSM technology.  Communication regulators in the Netherlands, Sweden, and the UK have created unlicensed spectrum bands for GSM use in the 1800MHz range. According to this OECD report, more than 3,000 organisations (hospitals, stadiums, etc) are using this spectrum to build their own private networks. That’s pretty remarkable. There is a trade-off with  unlicensed spectrum in that the power output limits have to be much lower on the GSM technology so that the signal does not propagate very far.   This makes it an ideal technology to deploy at a single building or complex, e.g. hospital, office building, stadium, etc. By keeping the power limits low, they don’t have to worry about interference.  1800MHz is also high enough up the spectrum band to limit propagation as well.  It would be worth pursuing unlicensed GSM regulation in emerging markets as a key to stimulating innovation and filling in gaps in coverage.

Dynamic GSM

Television White Spaces Spectrum (TVWS) or what is now known as Dynamic Spectrum is an approach to spectrum management in which frequencies are dynamically assigned via a geo-location database.  While geo-location databases were designed with television spectrum in mind, there is nothing to stop them being used for any frequency range.  Google are pursuing just this sort of approach in the 3.5GHz band.   It is plausible to suggest that a geo-location database approach might be used to make GSM spectrum available on a secondary basis in underserved communities.  This would really open the flood-gates to rural GSM solutions.  I suggested as much last year.  There are some potential obstacles to this happening quickly though. The first is the possibility of existing spectrum holders fighting the idea tooth and nail because the end-game implications of this is conceivably the end of traditional spectrum licenses.  Another possible problem is a more technical one. With television spectrum it is fairly easy to build a spectrum database. The location of television towers and transmitters as well as their power outputs are usually well-known by the regulator and can be used to build a good picture of spectrum occupancy.  For GSM spectrum, it would mean getting all that information from MNOs. This entails many more towers, technologies, etc. In theory this shouldn’t be that hard. In Canada, for instance, you can get that information from the regulator and build your own map of mobile towers but in most countries in sub-Saharan Africa, I suspect that information may be harder to extract from operators.  I have never seen a map of mobile towers but I sure would love to.

Finally I would be remiss if I failed to mention the brilliant innovation that researchers from UC Berkeley came up in using mobile handsets themselves to do dynamic spectrum sensing and automatically choose unused GSM spectrum. In this scenario, a geo-location database is not required as each basestation would self-regulate based on data reported from phones on the network. An idea so clever in its simplicity, it took my breath away the first time I read about it. Getting regulator buy-in though is likely to be tougher than the geo-location database approach even if this approach may be cheaper and more effective in the short-term.


Image courtesy Rhizomatica.org.  Title courtesy of Heineken